1. Field of the Invention
The present invention relates to an improved endless flexible print belt intended for "on-the-fly" printing. More particularly, the present invention relates to a character support for a printing apparatus in which printing impressions are formed by impacting the character support against a record or writing medium under the control of hammers.
The invention disclosed herein may take the form of an endless flexible print belt adapted for use with band printers; or may take the form of an annular band which is applied and secured to a cylindrical plastic or metal element to form a drum for use with drum printers; or may take the form of an annular band which is applied and secured to a plastic or metal part of generally circular configuration to form a print wheel for use with wheel printers.
2. Description of the Prior Art
It is common in the industry to utilize an endless metallic or stainless steel print belt having the characters and timing marks affixed thereon by either mechanical, chemical or electrical generation as is well known in the art. Such metal belts, when the ends are welded together, may warp or be out of line when in use thus rendering them ineffective. In some non-metallic belts, the character bearing elements or segments are affixed to the flexible belts by welding, gluing or by mechanical bonding.
The prior art metallic belts are expensive to produce since it is difficult to technically control the shape and contour of the belt. In printers manufactured today, the belt is stretched over two pulleys, one pulley being driven causing the metallic belt to move at a rather high velocity. Every time a given segment or portion of the metallic belt passes over a pulley on one end, severe internal stresses are induced or generated within the belt itself resulting in metal fatigue thus reducing the useful life of the belt. It is well known that the life of the metallic belt can be increased by maintaining the hardness of the metallic belt relatively soft, as an example, by utilizing a metal having a Rockwell hardness in the range of 40 to 45. While such soft metal belt may reduce belt fatigue, thereby tending to extend the life of same, another problem results. When paper, which is abrasive, is moved over the characters on the belt, it tends to abrade or wear the characters very rapidly thus reducing the life of the belt when softer metallic materials are used.
It has also been found that the endless metallic belts now utilized are designed for pulleys having an outside diameter of 5 inches or more. As the pulley size decreases the internal stresses within the driven belt increase very rapidly. This means that pulleys smaller than 5 inches outside diameter are not economically sound. This results in the equipment manufacturer utilizing rather large bulky heads and cabinets to encompass the machine. Therefore, the metallic print belts now utilized in the art have several problems which limit the useful life of the belt itself and also the life of the characters on the belt regardless of how the characters are applied to the belt. Thus whatever solutions have been adopted heretofore to extend the life of the metal belt per se or of the characters thereon, have not been economically or technically sound. This invention solves such problems.
United States patents disclosing endless belts are as follows: Helms, U.S. Pat. No. 3,845,711, dated Nov. 5, 1974; Deproux, U.S. Pat. No. 3,838,765, dated Oct. 1, 1974; Pittis, U.S. Pat. No. 3,826,191, dated July 30, 1974; Hansen, et al., U.S. Pat. No. 3,774,531, dated Nov. 27, 1973; Huntoon et al., U.S. Pat. No. 3,742,848, dated July 3, 1973; Bossi, U.S. Pat. No. 3,741,110, dated June 26, 1973; Picard, U.S. Pat. No. 3,724,371; dated Apr. 3, 1973; Niccolai, U.S. Pat. No. 3,719,139, dated Mar. 6, 1973; and Harrington, U.S. Pat. No. 3,665,852, dated May 30, 1972; however, none of said patents as well as other prior art patents known to us disclose an endless flexible print belt or character support utilizing a series of type carrying segments in endless array, with the characters and timing marks provided on each of the segments, and with the segments being held together in a close side by side relationship by reinforcing cords and by an elastic encapsulating or bonding material which will permit the belt or band to flex as it moves around a pulley of any size including a small diameter pulley.